In the field of MOS transistor integrated circuits, it has become the practice to form the gates of the transistors of polysilicon which is doped to make it conductive. Also, the polysilicon gates are generally used to mask the channel region of the transistors while forming the source and drain regions on opposite sides of the gates so that the source and drain regions are aligned with their respective gate. Recently, there has been developed integrated circuits which include both MOS transistors and bipolar devices so that the circuits can perform both analog and digital functions. In such circuits, since a layer of doped polysilicon is being provided for making the MOS transistors, it would be desirable to be able to use the polysilicon layer to perform additional functions, particularly in the bipolar devices.